This C++ code snippet does the following: 1. **`void main()`**: Declares...

This C++ code snippet does the following:

1. void main(): Declares the main function. Note that void main() is non-standard in C++; it should ideally be int main().

2. vector<int> v(5, 20);: Creates a std::vector named v with 5 elements, each initialized to the value 20. The vector will look like this initially: [20, 20, 20, 20, 20].

3. v[1] = 100;: Modifies the second element (index 1) of the vector v to have the value 100. After this operation, the vector will look like this: [20, 100, 20, 20, 20].

4. cout << v[0] << endl;: Prints the value of the first element (index 0) of the vector, which is 20, followed by a newline.

5. cout << v[1] << endl;: Prints the value of the second element (index 1) of the vector, which was modified to 100, followed by a newline.

Output of the Code:

The code will output:

20
100

Note: The code does not return any value (due to void main()), which could lead to undefined behavior in some systems. It is safer and standard to use int main() and have return 0; at the end.